Foot control using rotatable cover plate for dental equipment

ABSTRACT

A foot control for dental equipment wherein an electric handpiece and an air-driven handpiece can be controlled by a single foot control. The foot control is actuated by a rotatable cover plate which can be rotated at any position on its surface. The electrical portion of the foot control can be used for driving an electric handpiece in a forward and a reverse direction without the necessity of moving hand-operated switches. All switching is automatically controlled through the rotation of the dentist&#39;&#39;s foot. The speed of the electric handpiece is controlled by rotating the cover of the foot control, and the electrical controls have no contacting parts for varying the speed.

O United States Patent 1 3,596,102

[12] Inventor Gregor; W-Brooks 2,863.0! l2/I958 Riedl 200/6AX W Pl3.335.240 8Il967 Dhaens et al.. 20016 A X [21] Appl. No. 798,6713,145,304 8/l964 Bostrom et nl.... 250/239 [22) il d 1 I969 3.l7l,034211965 Tomasulo et al 250/239 [45] Pltented July 27,1971 3,358,15012/1967 -S ummer 250/211 X 73] Aulgnee Stu-Dental Muulneturlng Cm, incllkll 3,471,928 /1969 Blllln. ZOO/86.5 X

fa gfigim m r i Primary Examiner-{Welter Stolwein n I I nattorney-Caesar, Rmse, Bernstein & Cohen LE com ABSTFACT: foot controlfor dental equipment wherein an 28 cm 22 nn'hl It electnc handprece andan 3lldl'lVn handptece can be controlled by n tingle foot control. Thefoot control actuated by [52] U8. CL

a rotatable cover law which can bg rotated at my posifiun on 32/22,250/211, 250/239. 338/7 in surface. The electrical portion of the footcontrol can be IIIL A6lc19l00 used for driving an electric handpiece ina forward and a fleldolsenrchmnw. reverse direcflon wilhou the access ofmoving hank]- -5; nunizsonls. 23123933202 operated twitches. Allswltching is automatically controlled through the rotation of thedentist: foot. The speed of the {563 electric handpieee is controlled byrotating the cover of the UNITED STATES PATENTS foot control, and theelectrical controls have no contacting 2,762,89l 911956 Hill et a1.338/78 part: for varying the speed.

PATENTEH m2? m1 sum 01 {1F 10 E g m: 2% 23 NE m INVENTOR. GREGORY W.BROOKS A TTORAIEYS.

ATTORNEYS.

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saw us or 10 O 0 IO ELECTRIC HANDPIECE FOOT C ON TROL INVENTOR. GREGORYW. BROOKS aha/ W W8 Wu ATTORNEYS.

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FOOT CONTROL USING ROTATABLE COVER PLATE FOR DENTAL EQUIPMENT Thisinvention relates to a foot control for dental equipment, and moreparticularly, to a foot control that is adapted for regulating andactuating an electric dental handpiece and an air-driven dentalhandpiece.

Substantially all of the dental handpieces now being used by dentistsare controlled by foot pedals or other foot controls. Where a dentistwill utilize an air-driven dental handpiece and an electric handpiece,he must have a separate foot control for each of the handpieces. One ofthe features of the foot control of this invention is that controls areprovided for regulating and powering both an electric handpiece and anair-driven handpiece in one instrument.

Insofar as the foot controls for air-driven dental handpieces areconcerned, the present practice is to provide a vertically extendingpedal which a dentist will rotate by moving the side or front of hisfoot against the pedal in order to control the amount of air going tothe handpiece. The foot control is also adapted to regulate the amountof coolant water which passes through the handpiece during use. One ofthe shortcomings of utilizing this type of foot control is that thedentist must constantly move his foot by lifting the same in order toregulate the foot control.

A modified form of foot control which has recently been used is to havea depressable pedal. However, when using the depressable pedal thedentist must constantly raise and lower his foot in order to regulatethe control. Thus, it is seen that in both types of air foot controlscurrently in use, the dentist will normally support all of his weight onone leg, and must balance himself on that leg while attempting toregulate the air controls in the foot control by his other leg.

An improvement on the depressable pedal foot control has recently beenmade wherein a horizontal ring extends laterally around the entirecircumference of a central hub of the foot control. The foot control isused by the dentists stepping on any portion of the ring around itsentire circumference in order to regulate air-driven dental equipment.Although this foot control does have the advantage of being usable atany position of the dentist's foot, thereby giving the dentist completefreedom of movement when operating on a patient, it still suffers fromthe disadvantage that the dentist must support and balance himself on asingle leg while controlling the foot control with the other leg.

In another aspect of the invention of this application, all of theaforementioned disadvantages of the air-type foot controls are overcome,while at the same time obtaining the advantage of having completefreedom of movement for the dentist's foot. Thus, utilizing the footcontrol of this invention, the cover plate of the foot control, which isless than 1% inches above the floor, provides a resting position for thedentist's foot that will operate the control. Accordingly, the controlcan be completely regulated by the dentist's resting his foot on thecover plate and rotating his foot in order to actuate the control.Utilizing the control of this invention, the dentist will be able tosupport himself on both legs. Furthennore, since the cover plate can berotated at any position, the dentist will have complete freedom ofmovement when operating on a patient while being able to regulate hisequipment through the foot control.

The electrical aspect of the foot control also enjoys a number ofspecific advantages and novel features when considered against theelectrical foot controls of the prior art. One of the advantages is thefact that the dentist can rest his foot on the cover plate of the footcontrol, instead of having to use the vertically oriented rotatablepedals or the depressable pedals of the prior art. Thus, as in the caseof the air control system, the dentist will have complete balance onboth of his feet, and will be able to regulate the control solely byrotating the cover plate of the foot control.

Another advantage of the electrical system is that the speed control forthe handpiece connected to the foot control is effectuated bynoncontacting means. In the electrical controls presently in use, speedvariation of an electric handpiece is regulated by a variable resistorin the foot control. Mechanical contact must be made during rotation ofthe control pedal in order to vary the resistance, and accordingly varythe speed of rotation of the handpiece. There is a high incidence ofbreakage and repair made necessary when using this type of speedcontrol. The repair incidence using the noncontacting speed control ofthis invention has been found to be minimal.

A further advantage of the electrical aspect of the foot control of thisinvention is the fact that not only is the speed of rotation of themotor in the electric handpiece controllable, but also the direction ofrotation is controllable by the foot of the dentist. In the prior artelectric foot controls, a handoperated switch had to be moved in orderto reverse the direction of rotation of the motor in the handpiece.

Another feature of the foot control of this invention is the ease withwhich it may be moved around the dentist's chair in order to facilitateoperating on the patient. The foot controls presently being used areextremely heavy and bulky, and can only be moved with a great deal ofeffort. The foot control of this invention is lighter in weight, and forthis reason alone can be moved more easily. Furthermore, a continual aircushion is provided for the foot control which will effectively lowerthe weight of the foot control. Accordingly, the dentist can move thefoot control by sliding his foot against the edge of the same andapplying a small amount of pressure.

It is accordingly an object of this invention to provide a novel footcontrol for dental equipment.

It is another object of this invention to provide a foot control fordental equipment that is adapted for controlling an airdriven dentalhandpiece and an electrical dental handpiece.

It is a further object of this invention to provide a foot control forelectric handpieces wherein the speed of rotation of the handpiece iscontrolled by noncontacting means within the foot control.

These and other objects of this invention are accomplished by providinga foot control comprising a baseplate, a cover plate rotatably mountedon said baseplate, and lying in a plane substantially parallel to saidbaseplate, cam means secured to said cover plate, and means mounted onsaid base plate for controlling a dental handpiece, said cam meansadapted to actuate said controlling means when said cover plate isrotated.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a top plan view of the foot control of this invention;

FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG.1-,

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is an enlarged sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 4;

FIG. 6 is a view similar to FIG. 5, with parts broken away for thepurpose of clarity;

FIG. 7 is a sectional view of the valves used for the chip blower andcoolant water control of the air-driven dental handpiece;

FIG. 8 is a sectional view of the valve for controlling the speed ofrotation of an air-driven dental handpiece;

FIG. 9 is a sectional view taken along the line 99 of FIG. 4, andshowing the electrical control in the full off position;

FIG. I0 is a sectional view similar to FIG. 9, but showing theelectrical control in one full on position;

FIG. I! is an exploded perspective view of the two members forregulating the electrical controls;

FIG. I2 is a sectional view taken along the line 12-12 of FIG. 5;

FIG. 13 is a sectional view taken along the line 13-13 of FIG. 12;

FIG. I4 is a bottom plan view of the foot control of this invention, andtaken in the direction of line 14-14 of FIG. 4;

FIG. 15 is a fragmentary bottom plan view similar to part of FIG. 14,but with the central cover plate broken away;

FIG. I6 is an enlarged sectional view taken along the line 16-16 ofFIG.I4;

FIG. I7 is a diagram of the entire control system;

FIG. I8 is a plumbing diagram for the system;

FIG. 19 is a wiring diagram for the system;

FIG. 20 is a wiring diagram showing the circuitry for the electricalcontrols within the foot control;

FIG. 21 is a top plan view ofa modified embodiment of the cover plate ofthe foot control of this invention; and

FIG. 22 is a side elevational view of the cover plate of FIG. 21.

Referring now in greater detail to the various figures of the drawingswherein similar reference characters refer to similar parts, a footcontrol for dental equipment embodying the present invention isgenerally shown at in FIG. I. Device 30 basically comprises a base plate32 and a cover plate 34 rotatably mounted thereon. Cover plate 34 liesin a plane substantially parallel to the plane of base plate 32 (FIG.4).

As best seen in FIGS. 4 and 5, the upper surface of base plate 32includes a plurality of rollers 36 having shafts 38 circularly arrangedin slots 40. Each roller 36 is rotatably mounted in its associated sloton its shaft 38. Base 32 is provided with an upwardly extending cavity42 in its lower surface. A circular opening 44 passes through the topsurface of plate 32 and into cavity 42. A race 46 is provided adjacentopening 42 and a plurality of balls 48 is received in the race. Anarcuate slot 50 (FIGS. 4 and 14) passes through the top of base 32 andinto cavity 42.

Air valves 52, 54 and 56 are mounted in rectangular flattened sectionson the top surface of base plate 32 by mounting screws 58. Aphotoelectric light 60 is mounted in socket 61, which is in turn securedto angle bracket 62. Angle bracket 62 is in turn mounted on a printedcircuit board 64 which is secured on the top surface of base plate 32.The mounting of angle bracket 62 can be by any conventional means, suchas screw 66. A photoelectric cell 68 (FIGS. 4 and 6) is secured onprinted circuit board 64 by screws 70 (FIG. 6). An arcuate verticallyextending wall 72 having a flange 74 is mounted on printed circuit board64 by screws 76. As best seen in FIGS. 9 to [1, wall 72 includes arecessed portion 78 having a central substantially semicircular slot 80formed in the top surface thereof. A pair of microswitches 82 and 84(FIG. 6) is secured to printed circuit board 64 by screws 86.Microswitches 82 and 84 each include a contact finger 88.

As seen in FIGS. 2 and 5, base plate 32 is provided with a channel 90. Arim 92 bridges the channel. A flexible plastic sleeve 94 passes throughchannel 90. As seen in FIG. 3, plastic sleeve 94 houses an eight-lineelectrical cable 96 and four flexible air tubes 98, 100, I02 and 104.The connections of the air tubes and the electrical lines within thefoot control 30 will be explained in detail hereinafter.

The underside of base plate 32 is provided with a circular groove 106(FIGS. 4 and 14). As seen in FIGS. 14, groove I06 terminates at channel90. As seen in FIG. 14, groove 106 includes a lateral extension 108. Asseen in FIG. 12, a hole 110 is formed in base plate 32. Hole 110 is influid communication with hole 112 formed in valve 56. A washer 113 isused to provide an airtight seal.

A cover plate 114 is secured over groove or channel 106 and itsextension 108 by screws I16. The portion of cover plate 114 over groove106 is provided with a plurality of holes I18 which are in fluidcommunication with the groove. As best seen in FIG. 16, a disc 120 issecured on plate 1I4 adjacent each hole 118. Plate I14 and itsassociated discs can all be formed from steel.

A second plate 122 is secured over channel 90 by screws 124. As seen inFIG. 2, sleeve 94 rests on plate 122. A third plate 126 is secured overcavity 42 by screws I28. As seen in FIG. 4, an upstanding boss 130 issecured to plate 126 by screw I32. Referring again to FIG. 14, it isseen that a pad 134 extends around substantially the entire undersurfaceof plate 32. Pad 134 is preferably formed from hard rubber and iscemented in place. The pad terminates adjacent plate 122.

Valve 52 is shown in detail in FIG. 7. As will be explained hereinafter,valve 52 is used to control the water supply to an air-driven dentalhandpiece that utilizes a water spray. Valve 52 includes a body 136having a pair of mounting slots I38. The valve is mounted on base plate32 by passing screws 58 through the mounting slots I38. If desired, themounting slots can be eliminated, and the valve body can be mounted on aplate which is in turn secured to base plate 32 by screws. Body I36further includes an internally threaded hole 140 for incoming air and aninternally threaded hole 142 for outgoing air. As seen in FIG. 5,fittings I44 and 146 are secured in holes 140 and 142, respectively.

A ball retainer 148 is secured on the front end of valve body 136. Aball 150 is mounted within the retainer 148. Ball 150 is preferablyformed from a material having a low coefficient of friction, such asnylon. The forward end 152 of valve shaft 154 abuts ball 150. The rearend 156 of the valve shaft is frustoconical and is received in afrustoconical seat formed in body 136. An O-ring retainer I58 is formedon the rear end of valve shaft 154. An O-ring 160 is received within agroove in O-ring retainer 158 and abuts lip 162 on valve body 136, andis in sealing relation therewith.

O-ring retainer 158 includes a rearwardly projecting boss 164. A coiledcompression spring I66 is telescoped over boss I64 and abuts end cap168, which is threadedly received in body 136. An O-ring is used to forman airtight connection between end cap 168 and body 136. An O-ring I72is telescoped over the forward end I52 of valve shaft I54. The O-ring isheld in place by washer I74. A quick exhaust channel 176 is formed inthe forward portion 152 of valve shaft 154. Channel 176 has one end influid communication with the interior of valve body 136 and the otherend in fluid communication with the interior of ball retainer 148.

Valve 56 (FIG. 5) is used for supplying coolant air on air driven dentalhandpieces having built-in air blowers. Valve 56 is substantiallyidentical in construction to valve 52. However, channel 176 isunnecessary in valve 56, and can therefore be eliminated. Anotherdistinction is the formation of hole 112 (FIG. I2) in valve 56. Thishole does not appear in valve 52.

Valve 54 (FIG. 5) is shown in detail in FIG. 8. This valve is used forcontrolling the air used to rotate the turbine of an airdriven dentalhandpiece. Valve 54 is substantially identical to valve 52, with theexception that channel 176 has been eliminated, and a portion of theforward end of the valve shaft is reduced in size from the forward endused in valve 52. Accordingly, valve 54 includes a body 178 havingadjustment slots 180. An internally threaded hole 182 is provided forincoming air and an internally threaded hole 184 is provided foroutgoing air. Referring again to FIG. 5, a fitting I86 is secured inhole I82 and a fitting 188 is secured in hole I84.

A ball retainer 190 is mounted on the front of body I78, and has a ballI92 secured therein. The forward end 194 of valve shaft I96 abuts ball192 and the rear end I98 of the valve shaft is received in a socket inbody I78. An O-ring retainer 200 has an O-ring 202 mounted therein. TheO-ring abuts lip 204 of valve body 178, and is in sealing engagementtherewith. A spring 206 is telescoped over boss 208 projectingrearwardly from O-ring retainer 200. One end of spring 206 abuts O-ringretainer 200 and the other end abuts end cap 210. An O-ring 212 isprovided for the end cap. An O-ring 214 is used to seal the forward endof the valve body, and is held in place by washer 216.

As best seen in FIGS. 1 and 4, cover plate 34 is basically circularalong its outer perimeter, and is convex in cross section. A pluralityof raised ribs 218 is formed in the upper surface of the cover plate.Ribs 218 also include substantially vertical extensions 220 (FIG. 4)which are present on approximately 75 percent of the circumference ofplate 34, as seen in FIG. I. As

seen in FIG. 4, plate 34 includes a central upper cavity 222. A disc 224is held in cavity 222 by a screw 226 which projects through a hole 228in the cover plate. Disc 224 is held in the position shown by anundulating spring 230. If the spring 230 were not present, disc 224would drop vertically within cavity 222, in view of the fact that itssecuring screw 226 is freely slidable within hole 228.

Cam block 232 is mounted on the undersurface of cover plate 34 by screws234. As best seen in FIGS. 4 and 5, cam block 232 includes a cam surface236 which is adapted to contact the balls of each of valves 52, 54 and56, and depress said balls in order to open the valves. As seen in FIG.6, recesses 238 and 240 are provided in order to permit the balls of thevalve to be fully seated thereby insuring complete closing of the valveswhen the foot control 30 is not being used.

A plate 242 (FIG. 4) is mounted on the top surface of cam block 232 byone of the screws 234 (FIGS. 4 and 5). As seen in FIG. 4, the uppersurface of plate 242 is vertically spaced from the inner surface ofcover plate 34. As seen in FIG. 5, the outer edge 244 of plate 242 isarcuate. An arcuate wall 246 depends from plate 242.

As seen in FIGS. 9, and II, wall 246 has a lower edge 248 that tapersupwardly and terminates in a substantially semicircular notch 250. Wall246 has the same radius of curvature as wall 72, and as seen in FIG. 9,notches 80 and 250 form a substantially circular opening in walls 72 and246 when the foot control 30 is in its at rest position. While in thisposition, a beam of light from photoelectric light source 60 passesthrough the opening formed by notches 80 and 250 and is focused onphotoelectric cell 68, as indicated by arrow 252 in FIG. 4.

Cam block 232 includes a dependent boss 254 (FIG. 4) having a centralupwardly extending opening 256. Cover plate 34 is mounted on base plate32 by inserting boss 254 in opening 44 of base plate 32. When thusinserted, balls 48 will be received in a race 258 in cam block 232.Likewise, a horizontal shoulder 260 on the undersurface of the coverplate will ride on rollers 36. The cover plate is secured in place by asplit collar 262 which is received in a groove in boss 254. The collaris applied prior to the securernent of plate 126 on the base plate, andtherefore the boss 254 is readily accessible for the placement of thecollar. When the collar is in place, the cover plate 34 cannot beinadvertently removed from the base plate since any upward movement ofthe cover plate will cause the split collar 262 to abut the upper wallof cavity 42, as seen in FIG. 4.

A coiled spring 264 is telescoped over boss I30 (FIG. 4) and is receivedin opening 256 in boss 254. As seen in FIGS. 4 and I5, spring 264 isdouble coiled to provide a pair of Iongitudinally extending ends 266 and268, which lie in substantially the same horizontal plane. As seen inFIG. 4, a pin 270 is mounted in the undersurface of cam block 232. Asseen in FIG. 15, pin 270 is received in slot 50 of base plate 32. Asecond pin 272 is secured in the upper wall of cavity 42 of base plate32. As best seen in FIG. 15, the ends 266 and 268 of spring 264 bypasseach other and resiliently engage pins 270 and 272.

As seen in FIG. I2, cam block 232 includes a slot 274 adjacent ball I50of valve 56. A blade 276 is mounted in the undersurface of disc 224, andprojects into slot 274. The application of foot pressure against the topof disc 224, in the direction of arrow 278 (FIG. 12) will depress disc224 against the urging of spring 230. This in turn will force blade 276downwardly into slot 274, in the direction of arrow 280. As the blade276 is pushed downward into slot 274, it will contact ball 150 of valve56, thereby opening the valve.

In use, cover plate 34 is rotated on base plate 32. Rotation is easilyaccomplished by the movement of horizontal shoulder 260 (FIG. 4) of thecover plate on rollers 36. Lateral movement of the cover plate relativeto the base plate is prevented by balls 48 and the associated races 46and 258. The rotational movement of the cover plate relative to the baseplate is limited by the length of the slot 50 (FIG. I5). Thus, as seenin FIG. 4, the cover plate 34 includes a dependent pin 270 which isreceived in slot 50. The engagement of the pin 270 with either end ofthe slot 50 serves as a limit for the rotational movement of the coverplate. The at rest position for the cover plate is the position whereinpin 270 will be in the center of slot 50, as shown in FIG. 15.

As will be explained hereinafter, the foot control of this invention isactuated by rotation of cover plate 34 in a clockwise orcounterclockwise direction from its at rest position. The rotation isaccomplished by the dentist's resting his foot at any position on theupper surface of the foot plate, and pushing or pulling the foot platein the desired direction of rotation. The ribs 218 provide a frictionalsurface in order to aid in the movement of the cover plate by thedentist's foot. Another possible method of rotating the cover plate isto use the side of the foot against the substantially vertical ribs 220(FIG. 4). Thus, the vertically extending ribs provide a frictionalsurface whereby the edge of the dentist's foot can easily rotate thecover plate in either direction.

The spring 264 (FIG. I5) insures that the cover plate 34 will always bereturned to the at rest position shown in FIG. 15. When the cover plateis in this position, the foot control will be nonoperating. Assuming thecover plate 34 is rotated in the direction of arrow 282 shown in FIG.15, the pin 270 will be urged against spring extension 268. As the pin270 is rotated within slot 50, spring extension 268 will be moved to theouter extremity of the slot to the position shown at 268' in FIG. 15.When the dentist removes the pressure from the top of cover plate 34,spring extension 268 will return pin 270 from the position shown at 270'to the position shown in full line in FIG. 15. Thus, it should berecalled that pin 272 is fixed in base plate 32 and pin 270 is moved bythe cover plate. The overlapping of the spring extensions 266 and 268,as shown in FIG. I5, resiliently urges pin 270 to the position shown infull line in FIG. 15. Thus, when the pin 270 is moved to the positionshown at 270 in FIG. I5 by the rotation of the cover plate, the tensionon spring 264 is increased. Accordingly, as soon as the pressure on thefoot plate is removed, the pin will automatically be returned to theposition shown in full line. Likewise, when the cover plate is rotatedin the opposite direction, spring extensions 266 will be moved outwardlyunder the urging of pin 270, in the same manner as extension 268. Assoon as the pressure is removed from the foot plate, extension 266 willreturn pin 270, and the associated cover plate, to the position shown infull line in FIG. 15.

As pointed out above, the foot control 30 is usable for controlling bothair driven and electrically driven dental handpieces. An overall diagramfor the air and electrical controls is shown in FIG. 17. The entiresystem can be activated by inserting plug 284 into any convenientreceptacle. Lines 286 and 288 lead from plug 284 to a double-pole,double-throw switch 290. When it is desired to use the foot control 30for regulating an air-driven dental handpiece, switch 290 is closed toconnect lines 286 and 288 with lines 292 and 294. When the switch isclosed in this direction, only the air system will be operational. Inorder to use the electrical system, switch 290 is closed in the oppositedirection, thereby electrically connecting lines 286 and 288 with lines296 and 298, When thus connected only the electrical system will beoperational. When the switch 290 is not closed in either direction, butis in the position shown in FIG. I7, neither the electrical nor the airsystem will be operational.

When the air system has been rendered operational through the closing ofswitch 290 in the appropriate direction, a yellow signal light 300 willbe lit to indicate to the dentist that the air system is now usable withthe foot control. At the same time, air solenoid 302, which is normallyclosed, will be opened. The opening of the solenoid permits air 304,which is under pressure, to pass through tube 306, in the direction ofarrow 308. through the solenoid 302 and its air supply tube (see alsoFIGS. I and 2). After the air enters the foot control through tube 100,it passes into a coupling having three outlet nipples. A tube isconnected onto each of the outlet nipples,

with one tube being secured to each inlet fitting in valves 52, $4 and56 (see FIGS. 5, 6 7 and 8). Valves $2, 54 and 56 are normally closedand are in the position shown in FIGS. 7 and 8. In this connection, itshould be recalled that valve 56 is substantially identical in structureand function to valve 52 shown in FIG. 7.

Valves 52 and 54 are simultaneously opened by rotating cover plate 34 ina counterclockwise direction, as viewed in FIG. 1. As seen in FIG. 5,the rotation of cover plate 34 in a counterclockwise direction will alsorotate cam block 232 in the same direction, since the cam block issecured to the cover plate (FIG. 4). Accordingly, cam surface 236 willbe brought to bear against ball 150 of valve 52 and ball 192 of valve54. Balls I50 and 192 will then be depressed against the urging ofsprings I66 and 206, respectively, (FIGS. 7 and 8) by the action of thecam surface on the balls. Thus, as seen in FIGS. 7 and 8, when the ballsof the respective valves are depressed, the O-ring retainers B and 200and their associated O-rings will be moved rearwardly away from thevalve seat formed by lips I62 and 204, respectively. When the O-ringsare moved away from their seats, valves 52 and 54 will be opened. Atthis time, air which entered ports I40 and I82. will pass through thevalve bodies, and exit through ports I42 and 184, respectively.

Air leaving valve 52 will enter tube 104 (FIGS. 1 and 3) and proceed inthe direction of arrow 310 (FIG. I7) to water switch 312. Water switch312 is a conventional pneumatic diaphragm valve. Any diaphragm valveknown to the art can be used with this invention, and the specificstructure of the diaphragm valve forms no part of this invention. Waterswitch 312 controls the supply of water which enters the system at 3l4,and passes in the direction of arrow 316 through needle valve 318 to thediaphragm valve 312. When the water switch 312 in pneumatically openedby the air from line I04, water will pass through the switch into tube320 and enter an airdriven dental handpiece 322 in the direction ofarrow 324. The water will leave the handpiece 322 through a tube mountedadjacent the dental bur and will be used for cooling and lubricating therotating bur. Any air driven dental handpiece that utilizes a waterspray can be used in connection with the foot control of this invention,and the specific handpiece that is to be used forms no part of thisinvention. By way of example, the handpieces shown in U.S. Pat. Nos.3,074,167, 3.l20,706, and 3,199,196 can be used.

Referring again to FIG. 7, it is seen that a channel 176 is formed inthe forward end 152 of valve shaft I54. The purpose of this channel isto insure immediate cutoff of the water supply to handpiece 322 when thedentist removes his foot from cover plate 34 and the cam 232 is returnedto its at rest position shown in FIG. 5. Thus, channel I76 serves as aquickexhaust channel for any air pressure built-up between the valveseat 162 and the diaphragm valve of water switch 312 when the valve 52is closed. Accordingly, with the provision of channel I76, immediatelyupon the closing of the valve, any air pressure within theaforementioned area is immediately dissipated in the direction of arrows325 through channel I76 and out around ball 150. If the quick-exhaustchannel 176 were not present, the pressure against the diaphragm valvewould maintain the valve open for a short period of time after the useof the handpiece has been terminated by the dentist's removing his footfrom the foot control. In such case, water would continue to emanatefrom the handpiece, and this would be undesirable. The channel 176 inessence gives immediate cutofl' to the water supply when the dentistsfoot is removed from the foot control.

At the same time the air leaves through tube I04 to actuate the waterspray, air will also leave valve 54 through tube 102 (FIGS. 1 and 3). Asseen in FIG. I7, the air leaving through tube I02 travels in thedirection of arrow 326 to handpiece 322. This air will be used to drivethe turbine within the handpiece 322. It should be noted by reference toFIG. 5, that the greater the rotation of earn 232, the greater amountball I92 of valve 54 will be depressed. Referring to FIG. 8, it is seenthat the further ball I92 is depressed, the greater the opening in thevalve, and accordingly more air will pass through valve 54. The speed ofrotation of handpiece 322 is directly proportional to the amount of airpassing through the handpiece to rotate the turbine. Accordingly, thedentist can regulate the speed of rotation of the bur in the dentalhandpiece by regulat' ing the amount of rotation of the cover plate 34.The more the cover plate is rotated, the greater the speed of rotationof the dental bur.

The foregoing description of the air system applies to the use of an airdriven dental handpiece while using a water spray. When it is desired touse an air driven dental handpiece with an air spray serving as a chipblower, cover plate 34 is rotated in a clockwise direction, as viewed inFIG. I. As seen in FIG. 5, the rotation of cover plate 34 in a clockwisedirection will cause cam surface 236 to depress ball 192 of valve 54 andball I50 of valve 56. Accordingly, air will leave valve 54 in order todrive the air-driven dental handpiece 322 in exactly the same manner asoccurred with the rotation of the cover plate in a counterclockwisedirection. Thus, the greater the rotation of the cover plate, the moreair passing through valve 54, and consequently the greater the speed ofthe air turbine of the handpiece.

Simultaneously with the opening of valve 54, valve 56 will be openedwhen the cover plate is rotated in a clockwise direction. Accordingly,air will pass through valve 56 and leave foot control 30 through tube 98(FIGS. I and 3) Referring to FIG. 17, it is seen that the air tube 98proceeds in the direction of arrow 326 to handpiece 322, where it willserve to blow the chips from a drilled tooth and to cool the toothduring drilling. Any air-driven dental handpiece that utilizes abuilt-in chip blower can be used with the foot control of thisinvention, and here again, the specific handpiece fonns no part of thisinvention.

Quite often a dentist utilizing handpiece 322 will desire to use thehandpiece as a chip blower without actuating the air turbine. This canreadily be accomplished using foot control 30 by the dentist'sdepressing disc 224 (FIG. 4) on top of the foot control. The disc willthen be depressed against the urging of undulating spring 230 by thedentist's stepping on it. When the disc is depressed, blade 276 (FIG.12), depending from the bottom of the disc, will enter slot 274. As seenin FIGS. 5 and I2, the depression of the blade will push ball I50 ofvalve 56 inward, thereby opening the valve. Accordingly, air will passthrough the valve, proceed through tube 98 into handpiece 322, and leavethe handpiece through the air spray nozzle in the handpiece. The dentistcan thus use the handpiece as a chip blower by holding disc 224 in adepressed position, or he can use the handpiece for applying quickbursts of air to a drilled tooth by alternately applying pressureagainst disc 224 and releasing the pressure.

A plumbing diagram is shown in FIG. 18. As seen therein, the air supply304 includes an air filter 330 and an air regulator 332. Air regulator332 is used to control the pressure of the air entering foot control 30.The water supply 314 includes a water filter 334 and needle valve 318.Additionally, a finely adjustable needle valve 336 can be added. As aseparate attachment to the system, an air syringe shown in phantom in338 can be added. The air syringe forms no part of the foot control, butcan be used as an added instrument in connection with the system. Whenit is used, air for the syringe can be tapped through the air supplyline 306 by line 340. A needle valve 342 can be used for controlling theair to the air syringe. The air syringe can have its own hand actuatedon-ofi" valve, which is common to the art.

When it is desired to use foot control 30 for controlling an electrichandpiece, switch 290 (FIG. 17) is closed in order to bring lines 286and 288 in circuit with lines 296 and 298. When die switch 290 is closedin this manner, the air system is deactivated and can no longer becontrolled by the foot control 30. Accordingly, only the electricalsystem is now usable.

Lines 296 and 298 are connected to a power unit 344. The power unit isin turn connected to foot control 30 through an eight line electricalcable 96 (see also FIGS 1 and 3). An electric handpiece 346 is connectedto power unit 344 by lines 348 and 350. The electric handpiece 346 canbe any electric handpiece known to the art and the specific details ofthe handpiece form no part of this invention. Generally handpieces ofthis type include a small 24 volt electrically reversible motor that isused for rotating a dental bur in a clockwise and a counterclockwisedirection. The electrical system also includes a red signal light 352which is lit when switch 290 is closed to activate the electricalsystem.

A wiring diagram for the entire system is shown schematically in FIG.19. As seen therein, substantially all of the wiring which is externalof foot control 30 is contained in a metal housing, which is indicatedschematically at 354. The housing contains the wiring generally shown inFIG. 17, and the various control units, such as the power unit 344 andthe solenoid 302. Plug 284 is external of housing 354, and if desired, aground wire 356 can be used with plug 284. Lights 300 and 352 areexternal of housing 354 and serve to indicate to the dentist theposition of switch 290. Thus, when switch 290 is in the open positionshown in FIGS. 17 and I9, neither light 300 nor light 352 is lit. Whenthe arms of switch 290 are connected electrically to lines 292 and 294,thereby activating the air circuit, yellow light 300 is lit. When thearms of the switch 290 are connected electrically to lines 296 and 298,thereby activating the electrical circuit, red light 352 is lit.

The foot control 30 is used for regulating an electric handpiece in thesame manner as it is used for regulating an airdriven handpiece. Thus,in order to rotate the bur in an elec tric handpiece, all that isnecessary is for the dentist to rotate the cover plate of the footcontrol 30. Rotation of the cover plate in a clockwise direction causesthe rotation of a dental bur in the electric handpiece in one direction.Rotation of the cover plate in a counterclockwise direction causes therotation of a dental bur in the electric handpiece in the oppositedirection. The speed of rotation of the dental bur is directlyproportional to the amount of movement of the cover plate. Thus, thefarther the cover plate is rotated relative to its central position, thegreater the rotational speed of the dental bur.

The speed of rotation of the motor of the electric handpiece iscontrolled by the photoelectric light 60 and photoelectric cell 68 (FIG.4). So long as the cover plate is in its central position, as indicatedin FIG. 15, the motor of the electric handpiece does not rotate. At thisposition of the cover plate, the full beam of light from thephotoelectric light 60 is received on cell 68. The full beam of lightpasses through the hole formed by notches 80 and 250 (FIG. 9) invertically extending walls 72 and 246, respectively. As the cover plateis rotated in either direction, the wall 246 moves relative tostationary wall 72, since the cover plate is secured to plate 242 fromwhich wall 246 depends (FIG. 4). Thus, assuming cover plate 34 isrotated in a clockwise direction, as viewed in FIG. 1, then wall 246moves in the direction of arrow 358 in FIG. 10. When the wall 246 hasmoved to its farthest extent, to the position shown in FIG. 10, no lightpasses to cell 68 from light source 60. At this point, the motor of theelectric handpiece is rotating at its highest speed. When the dentistremoves the rotational force of his foot against cover plate 34, thecover plate automatically returns to its at rest position through theforce of spring 264 (FIG. With the cover plate thus returned, notches 80and 250 are again aligned, and the full beam of light from light source60 reaches photoelectric cell 68. At this time, the motor in theelectric handpiece is turned off because switches 82 and 84 whichinitially actuate the electric handpiece are turned off.

Assuming the dentist wishes to rotate the bur in the electric handpiecein the opposite direction, all that is necessary is to rotate the coverplate in a counterclockwise direction, as viewed in FIG. 1. At thistime, the wall 246 is moved in the direction opposite that shown byarrow 358. Here again, the rotational speed of the dental bur isdirectly dependent upon the distance the cover plate and its associatedvertical wall or flat 246 are rotated.

Referring again to FIG. 9, the taper 248 of wall 246 should be noted.Thus, it is seen in FIG. 9 that because of the taper 248, the amount oflight which is cut off by the rotation of wall 246 is graduallyincreased. This permits a gradual increase in the rotational speed ofthe motor of the electric handpiece. Thus, the light normally passesthrough the notch until the wall 246 is rotated to its farthest extent,which is shown in FIG. 10. As pointed out above, at this position, themotor of the electric handpiece is running at its highest rotationalspeed.

A wiring diagram for the speed control of the electric handpiece isshown in FIG. 20. The circuitry for the speed control within the footcontrol 30 is mounted on printed circuit board 64 (FIG. 5) which isshown as a block indicated in phantom in FIG. 20. Likewise, thecircuitry within power unit 344 is also shown schematically within ablock indicated in phantom in FIG. 20. The eight-wire cable 96 (FIGS. 1and 3) connecting the power unit 344 with the foot control isschematically indicated by hoop 96 in FIG. 20.

The circuitry within the foot control 30 includes the photoelectric lamp60 and the photocell 68 which are mounted on printed circuit board 64.Microswitches 82 and 84 (FIG. 6) are in circuit with diodes 360, 362 and364. The control circuitry within power unit 344 includes a transformer366, a full wave diode rectifier 368 comprising diodes 370, 372, 374 and376, and four transistors 378,380, 382 and 384.

The primary windings of transformer 366 are connected to lines 296 and298 (see also FIGS. 17 and 19). The transformer 366 includes twosecondary windings. A first winding is connected via lines 386 to thefull wave rectifier 368. The other secondary winding is connected vialines 388 to photoelectric lamp 60. A resistor 390 is provided in one oflines 388 to limit the amount of voltage to the photoelectric lamp 60 sothat it is compatible with the photocell 68.

The full wave rectifier 368 is connected via line 392 to capacitor 394which acts as a filter capacitor. A resistor 396 is connected acrosscapacitor 394 to act as a bleeder resistor, and further filters out theripples provided on the output of rectifier 368. The rectifier 368 isalso connected via line 398 to the other side of capacitor 394 andresistor 396.

The rectifier 368 is also connected to the emitter of transistor 378 vialine 398 and to potentiometer 400 via line 402. Potentiometer 400 isconnected at its other end to the resistor 404 which is connected at itsother end to line 398 and to the emitter of transistor 378. Thecollector of transistor 378 is connected via resistor 406 and line 408to the base of transistor 382. Potentiometer 400 is also connected tothe emitter of transistor 380 and to potentiometer 410 via line 412. Thewiper of potentiometer 400 is connected to the vase of transistor 378.

The emitter of transistor 380 is connected via resistor 414 to resistor416, and via line 418 to the emitter of transistor 384 and to photocell68. The other side of photocell 68 is connected in turn to terminals 420and 422 of switches 82 and 84, respectively. The resistor 416 isconnected at its other end to potentiometer 410, and via line 424 to theother side of photocell 68. Potentiometer 410 is connected at its otherend to the emitter of transistor 380 and to the base of transistor 380.It can be seen that the second end of potentiometer 410 is connected tothe wiper so that the resistance of potentiometer 410 can be varied tothe base of transistor 380.

Terminals 426 and 428 of switches 82 and 84, respectively, are connectedvia diodes 360, 362 and 364 to the emitter of transistor 380. Terminal430 of switch 82 is connected via line 348 to motor 432 of the electrichandpiece 346 (see also FIG. 17). Terminal 434 of switch 84 is connectedvia line 350 to motor 432 of handpiece 346 (see also FIG. 17). Thecollector of transistor 380 is connected via line 436 to resistor 438and to the base of transistor 382. Resistor 438 is connected at itsother end to line 392 and to the collector of transistor 382. Thecollector of transistor 382 is also connected to the collector oftransistor 384. The emitter of transistor 382 is connected to the baseof transistor 384. The emitter of transistor 384 is connected to thephotoelectric cell 68.

As set forth above, as the cover plate 34 is rotated off its center orat rest position, less and less light is transmitted from thephotoelectric lamp 60 to the photoelectric cell 68. The more light thathits photoelectric cell 68, the less resistive the photocell is.Conversely, the less light that is transmitted to the photocell, themore resistive the cell becomes. The photocell is placed across resistor416 and provides a voltage divider with potentiometer 410. The resistor416 is provided to improve the characteristics of the voltage signalacross the photoelectric cell 68.

The switches 82 and 84 are so connected to the motor 432 of electrichandpiece 346 that, depending on the direction of movement of the footcontrol cover plate 34, the polarity of the signal to the motor ischanged, thereby enabling the motor to be rotated in the directioncorresponding to the movement of the cover plate. As hereinabove setforth with respect to FIG. 6, the switches 82 and 84 include contactfingers 88 which are in contact with cam block 232. When the cover plateis moved in a first direction, the contact fingers 88 will be connectedto terminals 426 and 428 of switches 82 and 84 (FIG. When the coverplate is rotated in the opposite direction, the cam block will move thecontact fingers 88 to connect them with terminals 420 and 422 ofswitches 82 and 84, respectively. The fingers 88 are free of allcontacts when the foot control is in its at rest position, which isshown in FIG. 6.

It is therefore seen that depending on the direction of rotation of thecover plate, the motor 432 is rotated in one direction or the other. Asthe light is shielded from the photoelectric cell 68, the resistanceincreases, thereby causing a reduction of the resistance of transistor384. That is, when the foot control is in a position whereby the motoris supposed to be rotating slowly, a large portion of light fromphotoelec tric lamp 60 hits photoelectric cell 68, thereby causing theresistance in the cell to be small. This causes the voltage at the vaseof transistor 380 to be higher, which tends to saturate the transistor380, which thereby causes the emitter voltage of transistor 382 toincrease. As the emitter voltage of transistor 382 is increased, thetransistor 384 becomes more resistive. The more resistive the transistor384, the less voltage which is applied via the rectifier 368 throughtransistor 384 to motor 432. Thus, the motor rotates slowly. The speedof the motor is directly proportional to the voltage applied thereto.

As the foot control is moved either clockwise or counterclockwise, theamount of light from the photoelectric lamp to the photocell isdecreased, thereby causing the resistance of the photocell to increase,which in turn causes a reduction of voltage to the base of transistor380. The transistor 380 is thereby less saturated, causing an increaseof the voltage at the base of transistor 382, which thereby causes theemitter voltage to be reduced. As the emitter voltage of transistor 382is reduced, the resistance of transistor 384 is reduced, therebyenabling more voltage to be applied from the rectifier throughtransistor 384 to the motor 432.

It can therefore be seen that the speed of rotation of the motor isdirectly proportional to the amount of rotational movement of the footcontrol from its center or at rest position. As the foot control ismoved clockwise or counterclockwise, the amount of light that hits thephotoelectric cell 58 decreases, thereby causing an increase in theresistance of the photocell. When the cover plate is moved in onedirection, the fingers 88 cause the emitter of transistor 384 to beconnected to the leads of the motor applying a voltage of a firstpolarity which moves the motor in a first direction. If, however. thecover plate is moved in the opposite direction, the fingers 88 are urgedagainst the opposite contacts, thereby enabling line 412 to be connectedto the motor, which causes an opposite polarity voltage to be applied tothe motor. This in turn makes the motor rotate in the oppositedirection. in this connection, it should be recalled that walls 72 and246 (FIGS. 9 and it!) serve as flags to vary the amount of lightreaching photocell 68 from photoelectric light 60, thereby regulatingthe speed of rotation of the motor.

One of the novel features of the foot control of this invention is thefact that the speed of rotation of the motor in the electric handpieceis controlled by noncontacting means. Thus, in the prior art footcontrols, the speed of rotation of the motor was controlled by varyingthe resistance to the motor through the use of a variable resistor. Thisemailed the use of contacting elements which rubbed against each otherduring the rotation of the foot control. It has been found that inactual use the contacting elements are worn out in a short period oftime and must be replaced. This can cause a substantial loss of time tothe dentist, and can require a relatively costly repair bill. In thefoot control of this invention, the speed of rotation of the motor isdirectly dependent upon light intensity, and

there are no elements which must come into contact in order to varymotor speed during the operation of the foot control.

Although the invention has been described in connection with the use ofa photoelectric lamp and photocell for varying the speed of the motor,other noncontacting means can be used to accomplish the same result. Forinstance, the photoelectric light 60 can be replaced by an electric coiland the photoelectric cell 68 can be replaced by a magnetosensi' tivesemiconductor device, the resistance of which is varied by varying theflux of magnetic field therearound. A semiconductor device that can beused for such a purpose is the Sony Magnetodiode which is sold by SonyCorporation of Tokyo, Japan. When using the semiconductor device incombination with a flux-producing electric coil, the flux can be variedby making dependent wall or flag 246 of a flux-shielding material, suchas lead. The semiconductor device will operate in the same manner as thephotocell, whereby the amount of resistance will be dependent upon theamount of flux reaching the device. Any other nonwearing devices thatcan be used for varying resistance can be used in the foot control ofthis invention.

The elimination of the heavy large variable resistor by the foot controlof this invention permits the use of the low-profile design, in additionto the other functional and service advantages. Additionally, thevariable resistor foot control presently in use create a great deal ofheat, which is not generated by the foot control of this invention.

Another feature of the electrical aspect of the foot control of thisinvention is that the direction of rotation for the motor of theelectric handpiece is controlled by the foot of the dentist. Thus, aspointed out above, rotation of the foot control in a clockwise directionwill rotate the motor in a clockwise direction and rotation of the footcontrol in a counterclockwise direction will rotate the motor in acounterclockwise direction. In the foot controls presently in use,rotation of the pedal of the foot control is in a single direction. ifthe dentist wishes to change the direction of rotation of the motor, hemust manually change a hand-operated switch. Therefore, insofar as theelectric aspect of this invention is concerned, the dentist is givengreater freedom of use of his hands when using an electrical handpiece,since the rotation of the motor of the handpiece can be controlledsolely through the use of his foot.

One of the features of this invention is the low profile of the coverplate 34 of the foot control. In an actual embodiment of the invention,the foot control has a diameter of approximately 9% inches, and amaximum height of less than IV: inches. Because of this low profile, thedentist can conveniently rest his foot on the cover plate whileoperating on a patient. When it is desired to rotate the cover plate,the dentist merely applies a pressure against the top of the cover platein the direction that he desires to rotate the cover plate. The ribs 218provide a frictional surface to facilitate the rotation of the coverplate. The cover can also be rotated by the edge of the dentist's footby placing a force against the dependent ribs 200 (FIGS. I and 4). whendoing this, the dentist can rest both feet on the floor.

A frictional surface can be placed on the top and side of cover plate 34by means other than ribs 218 with dependent sections 220. Anotherembodiment of the cover plate is generally shown at 442 in FIG. 21.Cover plate 442 includes the central disc 224, and with the exception ofthe frictional surfaces, is identical in all respects to cover plate 34.The frictional surface of the cover plate 442 is provided by a pluralityof rings of separated ribs 444. Vertically extending ribs 446 areprovided at the edge of the cover plate to provide a frictional surfacefor the edge of the dentists foot.

It is to be understood that other friction-producing means can be usedin order to facilitate the use of the foot control of this invention.Thus, the tip and edge of the cover plate can be provided with anabrasive coating in order to obtain the desired friction. Alternatively,the top and edge can be provided with a knurled surface or with cutgrooves in the surface.

Having the low profile of the cover plate provides a distinct advantageover the foot controls of the prior art. Thus. in the prior art,regulation of the foot control for regulating speed was through avertically extending pedal which has to be moved by moving the dentist'sfoot, or through a horizontally extending pedal which has to bedepressed by the dentist's foot. Utilizing either of these foot controlsrequired the dentist to place substantially all of his weight on hisother foot. Accordingly, the dentist was continually in an unbalancedcondition when operating the foot control. Utilizing the foot control ofthis invention, the dentist's full weight can be placed on the footcontrol or the dentist's full weight can be placed on the floor while heis regulating the foot control with the side of his foot. Anotheradvantage of the rotatable cover plate is that the dentist can controlthe foot control at any position on the surface of the foot control.This gives the dentist greater freedom of movement in operating on apatient than could be obtained when using a fixed pedal on the side of alarge box, as is the case with the foot controls presently in use.

One of the features of the air control system of the foot control isthat the dentist can automatically go from wet cutting with an airdriven dental handpiece to dry cutting with the same handpiece solely byregulation of the cover plate. Additionally, the dentist can use hisair-driven dental handpiece solely as a chip blower by depressing disc224 on the cover plate. Merely by moving hand-operated switch 290 (FIGS.I7 and 19), the dentist can convert the foot control from use with anair-driven dental handpiece to use with an electric handpiece, or viceversa. None of the foot controls of the prior art have this completeversatility within a single unit.

Another feature of the foot control of this invention is the ease withwhich the dentist can move the foot control around his office in orderto make it accessible from various positions while he is working on apatient. All that is necessary to move the foot control is for thedentist to apply a lateral pressure with the side of his foot againstthe foot control. It has been found that the dentist can supplysufficient pressure with the side of his foot to slide the control toany desired position. However, the amount of pressure necessary to slidethe foot control is substantially greater than that needed to rotate thefoot control with the side of the foot. Thus, there is no fear ofinadvertently moving the foot control when the dentist is rotating thesame with the side of his foot.

The easy sliding of the foot control is accomplished by providing asmall air pressure on the underside of the foot control. In thisconnection, attention is again called to FIG. 12 wherein it is seen aport 112 is formed in the bottom of valve 56. Port I12 is in fluidcommunication with channel 108 (FIG. 14) which is in turn in fluidcommunication with channel I06. When the air system is turned on, airwill continually bleed through port I12 to channel I06. The air withinchannel 106 will be expelled through holes 118 in plate 114. The airwill be expelled in a downward jet, and will impinge on the floor belowthe cover plate. The discs 120 (FIG. I6) will aid in directing thestream of air downward. The bleeding air will cause a small air pressureto build up on the underside of base plate 32. Pad 134 will aid inmaintaining this pressure by providing a seal for the underside cavityof the base plate (see FIG. 4 for cavity). Pressure built up within thiscavity will effectively lighten the foot control 30 and permit the footcontrol to be slid across the floor by a lateral pressure against itsedge. The pressure is maintained by the continual discharge of air intothe cavity from the openings in cover plate 114.

In addition to being slidable across the floor, the foot control canalso easily be lifted and carried to any desired position by thedentist. There is no fear of the cover plate 34 coming ofl' duringmovement since the split collar 262 will hold the cover plate in place.

The foot control can be modified by substituting a second air system forthe electrical system. In this case switch 290 is used for convertingfrom one air system to the other. In this way two separate airhandpieces can be controlled by the foot control. One handpiece can be ahigh speed, contra-angle type and the other a low-speed high-torquestraight type. Alternatively, the second air system can be used forcontrolling an air syringe and a water syringe.

Without further elaboration, the foregoing will so fully illustrate myinvention, that others may, by applying current or future knowledge,adopt the same for use under various conditions of service.

I claim:

I. A foot control for dental equipment comprising a base plate, a coverplate rotatably mounted on said base plate, said cover plate having alateral surface sufficiently large to permit a dentist to place hisentire foot thereon, said cover plate comprising the top surface of saidfoot control, said cover plate being rotatable in a plane which issubstantially parallel to said base plate, means secured to said coverplate for actuating dental equipment, and means associated with saidactuating means for controlling said dental equipment, said actuatingmeans being operated only when said cover plate is rotated, whereby thedentist can place his weight on his foot on the cover plate withoutoperating said actuating means, and said controlling means beingregulated by the amount of rotation of said cover plate, said footcontrol having a ratio of height to width of less than 1:4.

2. The foot control of claim I wherein said base plate includes rollermeans therein and said cover plate rotates on said roller means.

3. The foot control of claim I wherein said cover plate is substantiallyconvex over its outer surface.

4. The foot control of claim I wherein said cover plate has frictionalmeans on the surface thereof.

5. The foot control of claim 4 wherein said frictional means comprises aplurality of upstanding ribs.

6. The foot control of claim 4 wherein said cover plate is substantiallyconvex over its outer surface, but additionally includes a substantiallyvertically extending outer rim, with said frictional means being presenton said convex surface and said outer rim.

7. The foot control of claim I wherein said actuating means comprises acam block, with said cam block being adapted to regulate said controlmeans.

8. The foot control of claim 7 wherein said foot control is adapted toregulate an air-driven dental handpiece, and said control meanscomprises a valve mounted on said base plate, with an inlet tubesupplying air to said valve and an outlet tube passing from said valveto said handpiece, said cam block having a cam surface adapted to opensaid valve, with the amount of opening of said valve being directlyproportional to the amount of rotation of said cover plate and itsassociated cam block, whereby the speed of rotation of the air-drivendental handpiece is directly proportional to the amount of rotation ofsaid cover plate.

9. The foot control of claim 8 and further including a second valve anda third valve mounted on said base plate, said cam block adapted tocontact said second valve and said third valve, an inlet tube adapted tosupply air to said second valve, an inlet tube adapted to supply air tosaid third valve, an outlet tube passing from said second valve to awater control switch, an outlet tube passing from said third valve tosaid handpiece, said second valve adapted to regulate the supply ofwater to said air-driven dental handpiece, said third valve adapted toregulate the supply of coolant air to said air-driven dental handpiece,said first mentioned valve and said second valve being adapted to beopened by said cam block when said cover plate is rotated in a firstdirection, and said first mentioned valve and said third valve beingadapted to be opened by said cam block when said cover plate is rotatedin a second direction.

10. The foot control of claim 2 and further including spring means formaintaining said cover plate at a set position with respect to said baseplate, with said cover plate being rotatable against the urging of saidspring means, whereby said spring means will return said cover plate tosaid position.

IL The foot control of claim 1 and further including means for limitingthe rotational movement of said cover plate relative to said base plate.

12. The foot control of claim I wherein said means for actuating saiddental equipment comprises a cam block, and said means for controllingsaid dental equipment includes switch means mounted on said base platewhich is controlled by said cam block, whereby the movement of said camblock against said switch means will actuate a dental handpieceassociated with said foot control.

13, The foot control of claim I wherein said controlling means isadapted to control an electric handpiece, said controlling meanscomprising variable resistance means, with the speed of rotation of themotor of said electric handpiece being controlled in accordance with theresistance of said variable resistance means, and spaced noncontactingmeans mounted on said base for varying the resistance of said variableresistance means as said cover plate is rotated.

14. The foot control of claim 13 wherein said controlling means furtherincludes switching means to enable said motor of said handpiece torotate in one of two directions in accordance with the direction ofrotation of said cover plate.

15. The foot control of claim 14 wherein said switching means arecontrolled by said actuating means.

16. The foot control of claim 13 wherein said spaced, noncontactingmeans comprise a photoelectric light and a photocell mounted on saidbase plate, with the light beam emanating from said photoelectric lightbeing received by said photocell, said cover plate including meanspositioned between said photoelectric light and said photocell to varythe amount of light passing to said photocell, thereby varying theresistance of said variable resistance means.

[7. The foot control of claim 16 wherein the means for varying theamount of light reaching the photocell comprises a wall depending fromsaid cover plate, with said wall adapted to be interposed between saidphotoelectric light and said photocell.

18. The foot control of claim I wherein said base plate includes asealed cavity in the lower side thereof, means for supplying air underpressure to said cavity, port means for exhausting air from said cavityto the underside of said base plate, and sealing means for maintainingthe air under said base plate, whereby said maintained air provides anupward lift on said base plate, thereby enabling said foot control to bemoved by the side of a user's foot.

19. The foot control of claim I wherein said foot control is adapted toregulate an air chip blower, valve means mounted on said base plate forcontrolling the air to said chip blower,

depressible means resiliently mounted in said cover plate, saiddepressible means having valve opening means depending therefrom,whereby said valve means can be opened by depressing said depressiblemeans and contacting said valve with said valve opening means,

20. A foot control for controlling an air-driven dental handpiece and anelectric handpiece comprising a base plate, a cover plate rotatablymounted on said base plate, said cover plate being rotatable in a planewhich is substantially parallel to said base plate, means secured tosaid cover plate for actuating said air-driven dental handpiece and saidelectric handpiece, switch means adapted to render the controls for theair-driven dental handpiece operational while preventing the operationof said electric handpiece, said switch means additionally being adaptedto render the controls for the electric handpiece operational whilepreventing the operation of said air-driven dental handpiece, and meansassociated with said actuating means for controlling said air-drivendental handpiece and said electric handpiece, said actuating means beingoperated when said cover plate is rotated, and said controlling meansbeing regulated by the amount of rotation of said cover plate,

21. The foot control of claim 20 wherein said electric handpieceincludes an electric motor, and said controlling means includesswitching means to enable said motor of said handpiece to rotate in oneof two directions in accordance with the direction of rotation of saidcover plate.

22. The foot control of claim 20 wherein said actuating means comprisesa cam block, said cam block being adapted to regulate said controllingmeans, and said controlling means is adapted to control said electrichandpiece, said controlling means comprising variable resistance means,with the speed of rotation of the motor of said electric handpiece beingcontrolled in accordance with the resistance of said variable resistancemeans, and spaced, noncontacting means mounted on said base for varyingthe resistance of said variable resistance means as said cover plate isrotated.

23. A foot control for an electric handpiece comprising a base plate, acover plate means rotatably mounted on said base plate, said cover platebeing rotatable in a plane which is substantially parallel to said baseplate, means secured to said cover plate for actuating said electrichandpiece, and means associated with said actuating means forcontrolling said electric handpiece, said controlling means beingregulated by the amount of rotation of said cover plate, saidcontrolling means comprising variable resistance means, with the speedof rotation of the motor of said electric handpiece being controlled inaccordance with the resistance of said variable resistance means, andspaced, noncontacting means mounted on said base for varying theresistance of said variable resistance means as said cover plate isrotated.

24. The foot control of claim 23 wherein said spaced, noncontactingmeans comprise a photoelectric light and a photocell mounted on saidbase plate, with the light beam emanating from said photoelectric lightbeing received by said photocell, said cover plate including meanspositioned between said photoelectric light and said photocell to varythe amount of light passing to said photocell, thereby varying theresistance of said variable resistance means.

25. The foot control of claim 24 wherein the means for varying theamount of light reaching the photocell comprises a wall extending fromsaid cover plate, with said wall adapted to be interposed between saidphotoelectric light and said photocell.

26. The foot control of claim 23 wherein said rotatable means isrotatable in two directions, and said controlling means further includesswitching means to enable said motor of said handpiece to rotate in oneof the two directions in accordance with the direction of rotation ofsaid rotatable means.

27. The foot control of claim 23 wherein said switching means arecontrolled by said actuating means.

28. The foot control of claim 23 wherein said rotatable means includesmeans adapted to be interposed between said spaced, non-contactingmeans, said resistance being dependent upon the location of saidinterposed means.

1. A foot control for dental equipment comprising a base plate, a coverplate rotatably mounted on said base plate, said cover plate having alateral surface sufficiently large to permit a dentist to place hisentire foot thereon, said cover plate comprising the top surface of saidfoot control, said cover plate being rotatable in a plane which issubstantially parallel to said base plate, means secured to said coverplate for actuating dental equipment, and means associated with saidactuating means for controlling said dental equipment, said actuatingmeans being operated only when said cover plate is rotated, whereby thedentist can place his weight on his foot on the cover plate withoutoperating said actuating means, and said controlling means beingRegulated by the amount of rotation of said cover plate, said footcontrol having a ratio of height to width of less than 1:4.
 2. The footcontrol of claim 1 wherein said base plate includes roller means thereinand said cover plate rotates on said roller means.
 3. The foot controlof claim 1 wherein said cover plate is substantially convex over itsouter surface.
 4. The foot control of claim 1 wherein said cover platehas frictional means on the surface thereof.
 5. The foot control ofclaim 4 wherein said frictional means comprises a plurality ofupstanding ribs.
 6. The foot control of claim 4 wherein said cover plateis substantially convex over its outer surface, but additionallyincludes a substantially vertically extending outer rim, with saidfrictional means being present on said convex surface and said outerrim.
 7. The foot control of claim 1 wherein said actuating meanscomprises a cam block, with said cam block being adapted to regulatesaid control means.
 8. The foot control of claim 7 wherein said footcontrol is adapted to regulate an air-driven dental handpiece, and saidcontrol means comprises a valve mounted on said base plate, with aninlet tube supplying air to said valve and an outlet tube passing fromsaid valve to said handpiece, said cam block having a cam surfaceadapted to open said valve, with the amount of opening of said valvebeing directly proportional to the amount of rotation of said coverplate and its associated cam block, whereby the speed of rotation of theair-driven dental handpiece is directly proportional to the amount ofrotation of said cover plate.
 9. The foot control of claim 8 and furtherincluding a second valve and a third valve mounted on said base plate,said cam block adapted to contact said second valve and said thirdvalve, an inlet tube adapted to supply air to said second valve, aninlet tube adapted to supply air to said third valve, an outlet tubepassing from said second valve to a water control switch, an outlet tubepassing from said third valve to said handpiece, said second valveadapted to regulate the supply of water to said air-driven dentalhandpiece, said third valve adapted to regulate the supply of coolantair to said air-driven dental handpiece, said first mentioned valve andsaid second valve being adapted to be opened by said cam block when saidcover plate is rotated in a first direction, and said first mentionedvalve and said third valve being adapted to be opened by said cam blockwhen said cover plate is rotated in a second direction.
 10. The footcontrol of claim 1 and further including spring means for maintainingsaid cover plate at a set position with respect to said base plate, withsaid cover plate being rotatable against the urging of said springmeans, whereby said spring means will return said cover plate to saidposition.
 11. The foot control of claim 1 and further including meansfor limiting the rotational movement of said cover plate relative tosaid base plate.
 12. The foot control of claim 1 wherein said means foractuating said dental equipment comprises a cam block, and said meansfor controlling said dental equipment includes switch means mounted onsaid base plate which is controlled by said cam block, whereby themovement of said cam block against said switch means will actuate adental handpiece associated with said foot control.
 13. The foot controlof claim 1 wherein said controlling means is adapted to control anelectric handpiece, said controlling means comprising variableresistance means, with the speed of rotation of the motor of saidelectric handpiece being controlled in accordance with the resistance ofsaid variable resistance means, and spaced non-contacting means mountedon said base for varying the resistance of said variable resistancemeans as said cover plate is rotated.
 14. The foot control of claim 13wherein said controlling means further includes switching means toenable said motor of said handpiece to rotate in one of two directionsin accordance with the direction of rotation of said cover plate. 15.The foot control of claim 14 wherein said switching means are controlledby said actuating means.
 16. The foot control of claim 13 wherein saidspaced, noncontacting means comprise a photoelectric light and aphotocell mounted on said base plate, with the light beam emanating fromsaid photoelectric light being received by said photocell, said coverplate including means positioned between said photoelectric light andsaid photocell to vary the amount of light passing to said photocell,thereby varying the resistance of said variable resistance means. 17.The foot control of claim 16 wherein the means for varying the amount oflight reaching the photocell comprises a wall depending from said coverplate, with said wall adapted to be interposed between saidphotoelectric light and said photocell.
 18. The foot control of claim 1wherein said base plate includes a sealed cavity in the lower sidethereof, means for supplying air under pressure to said cavity, portmeans for exhausting air from said cavity to the underside of said baseplate, and sealing means for maintaining the air under said base plate,whereby said maintained air provides an upward lift on said base plate,thereby enabling said foot control to be moved by the side of a user''sfoot.
 19. The foot control of claim 1 wherein said foot control isadapted to regulate an air chip blower, valve means mounted on said baseplate for controlling the air to said chip blower, depressible meansresiliently mounted in said cover plate, said depressible means havingvalve opening means depending therefrom, whereby said valve means can beopened by depressing said depressible means and contacting said valvewith said valve opening means.
 20. A foot control for controlling anair-driven dental handpiece and an electric handpiece comprising a baseplate, a cover plate rotatably mounted on said base plate, said coverplate being rotatable in a plane which is substantially parallel to saidbase plate, means secured to said cover plate for actuating saidair-driven dental handpiece and said electric handpiece, switch meansadapted to render the controls for the air-driven dental handpieceoperational while preventing the operation of said electric handpiece,said switch means additionally being adapted to render the controls forthe electric handpiece operational while preventing the operation ofsaid air-driven dental handpiece, and means associated with saidactuating means for controlling said air-driven dental handpiece andsaid electric handpiece, said actuating means being operated when saidcover plate is rotated, and said controlling means being regulated bythe amount of rotation of said cover plate.
 21. The foot control ofclaim 20 wherein said electric handpiece includes an electric motor, andsaid controlling means includes switching means to enable said motor ofsaid handpiece to rotate in one of two directions in accordance with thedirection of rotation of said cover plate.
 22. The foot control of claim20 wherein said actuating means comprises a cam block, said cam blockbeing adapted to regulate said controlling means, and said controllingmeans is adapted to control said electric handpiece, said controllingmeans comprising variable resistance means, with the speed of rotationof the motor of said electric handpiece being controlled in accordancewith the resistance of said variable resistance means, and spaced,noncontacting means mounted on said base for varying the resistance ofsaid variable resistance means as said cover plate is rotated.
 23. Afoot control for an electric handpiece comprising a base plate, a coverplate means rotatably mounted on said base plate, said cover plate beingrotatable in a plane which is substantially parallel to said base plate,means secured to said cover plate for actuating said electric handpiece,and means associated with said actuating means for controllIng saidelectric handpiece, said controlling means being regulated by the amountof rotation of said cover plate, said controlling means comprisingvariable resistance means, with the speed of rotation of the motor ofsaid electric handpiece being controlled in accordance with theresistance of said variable resistance means, and spaced, noncontactingmeans mounted on said base for varying the resistance of said variableresistance means as said cover plate is rotated.
 24. The foot control ofclaim 23 wherein said spaced, noncontacting means comprise aphotoelectric light and a photocell mounted on said base plate, with thelight beam emanating from said photoelectric light being received bysaid photocell, said cover plate including means positioned between saidphotoelectric light and said photocell to vary the amount of lightpassing to said photocell, thereby varying the resistance of saidvariable resistance means.
 25. The foot control of claim 24 wherein themeans for varying the amount of light reaching the photocell comprises awall extending from said cover plate, with said wall adapted to beinterposed between said photoelectric light and said photocell.
 26. Thefoot control of claim 23 wherein said rotatable means is rotatable intwo directions, and said controlling means further includes switchingmeans to enable said motor of said handpiece to rotate in one of the twodirections in accordance with the direction of rotation of saidrotatable means.
 27. The foot control of claim 23 wherein said switchingmeans are controlled by said actuating means.
 28. The foot control ofclaim 23 wherein said rotatable means includes means adapted to beinterposed between said spaced, non-contacting means, said resistancebeing dependent upon the location of said interposed means.